How to use F() expression to flip the boolean field

[jay.sh...@gmail.com]

Hi there,
I'm using django 1.1 beta now. There is a boolean column in my table.
I want to filp all the value, that is True to False and False to
True.
I found the F() expression in django 1.1 beta, and tried to use to to
satisfy my request but failed.
Here is my usage:
= code start =
class SomeModel(models.Model):
  display = models.BooleanField('display', default = False)

SomeModel.objects.update(display = not F('display'))
== code end ==

Did I make something wrong in the query? If so, how to fix it?
Many thanks!

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How to customize field to get the correct python value?

[jay.sh...@gmail.com]

Hi there,

I have a question on customize the db field. For this field, I want to
save integers in db, but want them to be my custom class when they are
used in Python code. In Django docs, it's said that I should set the
__metaclass__ to be models.SubfieldBase to make to_python() work. I
tried it and succeeded when all data of one db row are fetched.

But I then found that if I use query method like values(), values_list
() or only(), the data of my custom field will not be converted into
my desired type but the raw db integer. Then I tried Django's own
DateField, it works OK also in such scenario. So I think there must be
something I missed.

Could you help on this question? I cannot find more materials to move
on, so I'm very eager to get your help. Many thanks!

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